Polyoxometalate-derived WSSe nanoparticles confined in carbon nanofibers for fast and durable lithium storage

Tungsten disulfide is a promising anode material for lithium-ion batteries (LIBs) owing to its high theoretical capacity, natural abundance, and environmental benignity, but its practical implementation is constrained by sluggish charge-transfer kinetics, large cycling-induced volume variation, and rapid capacity fading. Herein, we report a synergistic heteroanion substitution and carbon confinement strategy to stabilize the electrode architecture by encapsulating selenium-substituted WSSe nanoparticles in nitrogen/phosphorus-codoped porous carbon nanofiber (WSSe@NP-CNF) via a polyoxometalate-derived electrospinning method. Combined in-situ/ex-situ characterizations and theoretical calculations reveal that the Se substitution modulates the electronic structure of WSSe, promotes charge redistribution, and lowers the kinetic barrier for lithium storage, whereas the interconnected porous carbon nanofiber network affords continuous Li⁺/electron transport channels and mechanically buffers structural evolution during repeated cycling. Benefiting from this dual regulation, the WSSe@NP-CNF anode delivers a high specific capacity of 822.3 mAh g^-1 at 0.1 A g^-1, superior rate capability of 379.9 mAh g^-1 at 5 A g^-1, and durable cycling durability with 90.1% capacity retention after 1000 cycles at 2 A g^-1. Impressively, the assembled LiFePO₄||WSSe@NP-CNF full cell exhibits exceptional long-term stability, maintaining 100% capacity retention over 2400 cycles at 1 A g^-1. This work highlights a rational electrode-design strategy that integrates heteroanion-regulated reaction kinetics with conductive carbon confinement, offering a viable route toward high-performance transition-metal chalcogenide anodes for advanced LIBs.